What do renewable and non-renewable mean? Energy resources can be classified into two groups. Renewable Non-renewable Renewableenergy resources can be replaced or regenerated and will never run out (at least not for a very long time). Non-renewable energy resources will eventually run out – once used they cannot be used again. Examples: wind and solar. Examples: coal and oil.
Spot the energy resources How many different energy resources are part of this scene?
What are fossil fuels? Industrial societies need a lot of energy and, at the moment, rely on fossil fuels as the main source of this energy. Coal, oil and natural gas are fossil fuels. They are carbon-based materials that formed over millions of years from the remains of ancient plants and animals. Fossil fuels are so useful because they contain stored chemical energy, which is converted into large amounts of useful heat energy when the fuels are burned. The total amount of fossil fuels available is limited and so they are classed as non-renewable energy resources.
How do fossil fuels produce electricity? Power stations that are fuelled by coal and oil, operate on the same basic principle. The fuel is burned and the heat produced is used to boil water. This creates high-pressure, superheated steam, which is then used to turn a turbine. The turbine turns a generator and so generates electricity. The cooling towers cool the steam, which condenses as water and can then be recycled in the power station. Natural-gas-fired power stations do not use steam. The natural gas is burnt and the hot gases produced are used directly to turn the turbine.
What can be done to reduce the problems caused by burning fossil fuels? What waste do fossil fuels produce? Burning fossil fuels creates waste products that can act as pollutants and have harmful environmental effects. • Carbon dioxide – This greenhouse gas is the main waste product of burning fossil fuels. Increased levels of carbon dioxide due to human activities are thought to be connected with global warming. • Sulfur dioxide and nitric oxides – These gaseous pollutants contribute to the formation of smog and acid rain. • Ash– This waste solid is disposed of in landfill sites.
What is nuclear fuel? Nuclear fuel is used to generate electricity but, unlike fossil fuels, it does not burn. In a nuclear fuel, such as uranium, reactions take place that split the atoms and release huge amounts of heat energy. This is called nuclear fission. In a nuclear power station, the heat released from nuclear fission reactions is used to change water into steam. As in other types of power station, the steam then turns a turbine, which turns a generator and produces electricity. Nuclear power stations do not release any greenhouse gases such as carbon dioxide or gases which cause acid rain.
What waste does nuclear power produce? Nuclear power stations produce radioactive waste. The used nuclear fuel contains some uranium, which can be separated from the waste and reused. It also contains plutonium, which is a highly-radioactive product of the fission reactions that occur in uranium nuclear fuel. New reactors that use this waste product as a fuel have been built. However, plutonium is also used in the construction of nuclear bombs and poses a very serious threat if it gets into the wrong hands.
Where can nuclear waste be stored? Nuclear waste that cannot be reused poses serious problems as it can remain radioactive for thousands of years. Highly radioactive waste can be turned into glass to help stabilize it and prevent leaks during storage. One solution is to bury the waste deep underground. This must be in a geologically stable environment, so there are few suitable sites. Another suggested solution is to dump radioactive waste at the bottom of the sea. Dealing with nuclear waste is expensive and any solution has to be long term.
How quickly can electricity be produced? Type of fuel Start-up time natural gas 1 hour 4 hours oil coal 7 hours nuclear power 48 hours Which type of power is useful when extra power is needed for a short time? The demand for electricity varies depending on the time of day and time of year. Power stations have to cope with this. Power stations cannot be turned on at the flick of a switch. These are typical start-up times for power stations that use non-renewable energy resources. Natural gas power stations produce electricity quickly. Nuclear power stations take about two days to reach full power. They are only shut down for maintenance.
Type of fuel Time until reserves run out natural gas 25-30 years about 75 years oil about 300 years coal nuclear power thousands of years How long can non-renewable energy last? Non-renewable energy resources will eventually run out. Scientists think that natural gas reserves will only last another 25-30 years. It is difficult to be exact as new gas fields are still being discovered. Even though nuclear fuel will last thousands of years, there is still a limited supply and so it will eventuallyrun out. This is why nuclear power is classed as a non-renewable energy resource.
Advantages of fossil fuels Disadvantages of fossil fuels Fossil fuels: what are the pros and cons? What are the advantages and disadvantages of burning fossil fuels in power stations to generate electricity? readily available non-renewable acid rain easily transported greenhouse effect low fuel cost inefficient low building costs short start-up times
Advantages of nuclear power Disadvantages of nuclear power Nuclear power: what are the pros and cons? What are the advantages and disadvantages of using nuclear power to generate electricity? cheaper to run once built expensive to build non-renewable conserves fossil fuels produces radioactive waste no sulfur dioxide emissions expensive to decommission no carbon dioxide emissions links with cancer safe under normal conditions small amount of fuel used so less transport needed risk of disaster
Glossary (1/2) • acid rain – Rainwater that is more acidic than normal due to the release of sulfur dioxide and nitrogen oxides into the atmosphere by burning fossil fuels. • fossil fuels –Carbon-based fuels, such as coal, oil and natural gas, that are formed over millions of years from the remains of ancient plants and animals. • generator –A device used in power stations, which transforms kinetic energy into electrical energy. • global warming – The increase in the temperature of the Earth, which some scientists think is causing climate change. • greenhouse effect – The trapping of heat from the Sun by certain gases in the Earth’s atmosphere. • greenhouse gas– A gas, such as carbon dioxide, that can trap heat from the Sun in the Earth’s atmosphere.
Glossary (2/2) • nuclear fission – The splitting of an atomic nucleus, which releases large amounts of energy. In nuclear power stations, this process provides the heat used in generating electricity. • nuclear fuel – Material, usually uranium, that undergoes nuclear fission and is the source of heat in nuclear power stations. • non-renewable – An energy resource that cannot be replaced or used again and so will eventually run out. • renewable – An energy source that can be replaced or regenerated and so will not run out. • turbine –A device used in power stations, which is turned by the force of moving steam. It is connected by a shaft to a generator to produce electricity.